fuel tank woes

Completed tank a few weeks ago. Test showed leak bubbles at sight glass. Talked with Van's and was told all I could do was remove front plate, and re -seal sight glass with the goop. Now I am not going to sit here and whine about how difficult it is to add goop to the sight glass area thru the front mount plate opening, but I will say that it's almost impossible to do it effectively. After all once your arm is in the opening there is essentially no way to see the area clearly. Ok, I did that anyway and left tank sit for two weeks while away. Tested it tonite and get bubble leak indications at 7 locations on the sight glass. I do not plan to remove the front plate again as that exercise is one in futility. Will smearing goop in the sight glass holes, and then cleaning excess (or just enough to see the glass) from the holes work? Has anyone done this with success? I will happily entertain any other suggestions as well from those who have been there. Thanks in advance.
Dick Seiders

Curious

Did you install the latest window and backing plate ? Was your 'goooo' gray or black when mixed ? Just a cheap guess, but I think trying to seal it the way you mentioned will be tough at best.

John Bender ( RV-12 tank specialist ! )

tank woes

My 12 received the new glass, and I installed using Van's supplied sealant. Sealant is dark gray when mixed thourghly.
Dick

To pass your inspection you're going to have to take the top off and re-do it...many of us did just that. Many of since inspection have covered up the sight glass (as you have discovered, a leak waiting to happen) and either gone to another float/gauge device on top or in my case...a stick in the tank with appropriate markings. You need something to preflight your fuel level besides the EFIS.

Its not that big a deal to take the top off and you can get it the holes sealed for long enough to pass...then cover em so you don't risk the leak or broken plastic in flight. As John says, good luck trying it from the outside...didn't work for me.

I feel completely safe with my set up now as I know John does with his.

Sorry Dick - - - -

If you have that many leaks, you will find it hard to just 'patch it up' even with the top off. You might want to get a new glass, and start over with a good mix of 'goooo'. Stay in a cooler place if you can - it will slow down the curing. Once finished, then put it where it is warm. Get a good smooth ribbon on the edge of the glass. Follow the instructions. As I recall the cutouts in the glass, you will find it hard to cover the entire thing, 'in place', and be sure it is sealed. SORRY !

John

Dick - another thought

BE CAREFUL with this ( I was reluctant to say this before, but it might save you tons of time ) Take the top off. Do whatever you want to do, either start over with the window, or patch if you prefer. Make some type of absolutely secure blocking system and set the tank at a 45 degree angle with the window facing down. Fill the tank ( with the top off ) with kerosene ( less flamable ), up to the top of the window, and see if the window leaks. Be sure you are in a safe, or outdoor area to do this. It might save you time, BUT IT IS DANGEROUS if not done carefully.

John Bender

Tank Trouble

Well, it looks like tank troubles are going to continue to plague us RV-12 builders, with no solid solution in site. Surely someone out there knows a fiberglass fabricator who can duplicate our little 20 gal tank, into a trouble free fiberglass, drop in unit, market it to us at an attractive price and still make a profit in the process. Sure, we may have to give up a little weight, but I sure think that it would be worth it. It's bad enough to have wing tank leaks, but a cabin area gas tank leak just scares the cr#% out of me. I've seen old boats rot away around a fiberglass tank, and never see a leak.

Lets take a look at what we have: A thin aluminum 20 gal box that we pop rivet together, with big gaping holes in the corners that we plug up with goo. Then we cover a bunch of holes that are running up and down one side with a piece of plastic! Oh yes, more goo. The kicker is taking an aluminum bulkhead fitting, and tightening the jam nut, with the expectation that you will be able to attach and remove the return line, through a little hole in the bottom of the fuselage. without causing another leak. Oh yes, and don't forget to add a little more goo. Now go fly this thing around in a little turbulent air, with 120 lbs of gas sloshing around in it for a couple hundred hours!! So, what am I missing? We need an alternative!!

Just my thoughts
Tom

Knock on wood, my tank has been fine.

I know when I installed the site glass I gooped the window and each screw. No leaks, no cracks.

todehnal said:

Well, it looks like tank troubles are going to continue to plague us RV-12 builders, with no solid solution in site. Surely someone out there knows a fiberglass fabricator who can duplicate our little 20 gal tank, into a trouble free fiberglass, drop in unit, market it to us at an attractive price and still make a profit in the process. Sure, we may have to give up a little weight, but I sure think that it would be worth it. It's bad enough to have wing tank leaks, but a cabin area gas tank leak just scares the cr#% out of me. I've seen old boats rot away around a fiberglass tank, and never see a leak.

Lets take a look at what we have: A thin aluminum 20 gal box that we pop rivet together, with big gaping holes in the corners that we plug up with goo. Then we cover a bunch of holes that are running up and down one side with a piece of plastic! Oh yes, more goo. The kicker is taking an aluminum bulkhead fitting, and tightening the jam nut, with the expectation that you will be able to attach and remove the return line, through a little hole in the bottom of the fuselage. without causing another leak. Oh yes, and don't forget to add a little more goo. Now go fly this thing around in a little turbulent air, with 120 lbs of gas sloshing around in it for a couple hundred hours!! So, what am I missing? We need an alternative!!

Just my thoughts
Tom

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Ya know Tom, I had a guy in Ft Worth call me after I finished my 12 and asked if I thought there would be any market for a fiberglass/carbon fiber tank. I told him I would buy one tomorrow. He even came over and took measurements etc. He had replaced the gas tank in his own car with such a tank. Never heard from him again. I'm kinda like you. Van's did it because they are metal people. But you would think the aftermarket opportunity would excite somebody...apparently not.

todehnal said:

Well, it looks like tank troubles are going to continue to plague us RV-12 builders, with no solid solution in site.
Tom

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I guess using that viewpoint it could be said that the tanks on all of the other RV's modles should have some redesign since even though there are thousands of them flying, their is always a certain percentage of builders that have leaks.

Their is no reason that the sight window should be any more prone to leaking (other than because of the failure of the material, which has been corrected) than the front access cover. I will admit that it is more of a challenge because you are working from within the tank instead of on the outside but with a little care it is not a problem. I have done it twice with no leaks.
Anyone that is concerned about it should just remove the top of the tank. This can be done in as little as 15 minutes.

Just my guess

Liability is likely the reason. At best they would only sell a few. Low volumn, high liability, not worth it.

John

that would keep me away, but I don't think innovators think in liability terms...everything in any aircraft is subject to liability. I think more likely is the lack of any guarantees (everyone has to eat). Only 16 flying, small chance of becoming OEM.

Sooner or later

somebody will produce for us a glass (of some sort) tank. Just a matter of time. Or we'll find a tank that is already in production and replace the aluminum tank that way. And I'd like a few more gallons - maybe 25?

Leaking gasoline isn't good anywhere much less within a few feet of my very perishable body. Hope that Van's will make the change eventually.

That's my opinion - and I am open to 'education' from you all.

Dick,

Sorry about your tank troubles. I feel your pain! I guess I was lucky. My tank hasn't had any gas in it yet but it loves to keep a balloon inflated!

For my two cents - I would just bite the bullet and drill out the top rivets. You will have to order some replacements. IMHO that is the only practical way to redo the site gauge. Take it all apart, clean it up real good, and do it over. Takes less time than fretting about it and trying half-measures like trying to put more goop in there with your hand in that hole.

Let us know how you make out.

John

rvbuilder2002 said:

I guess using that viewpoint it could be said that the tanks on all of the other RV's models should have some redesign since even though there are thousands of them flying, their is always a certain percentage of builders that have leaks.

Their is no reason that the sight window should be any more prone to leaking (other than because of the failure of the material, which has been corrected) than the front access cover. I will admit that it is more of a challenge because you are working from within the tank instead of on the outside but with a little care it is not a problem. I have done it twice with no leaks.
Anyone that is concerned about it should just remove the top of the tank. This can be done in as little as 15 minutes.

Click to expand...

Hi Scott,

Yes there are many of you quick build tanks that leak, some real leaks and some that just leak fumes through the rivets and mess up the paint. The good part is that these tanks are in the well ventilated wing part of the aircraft and not less than a foot from the pilots head and nose, so except for the real flowing leaks it is just a problem not a big deal.

The tank top is the problem instead of the solution, anyone can get the other five sides sealed up with just normal workmanship as we can see what we are doing and when we have got it right. We all can even get a good coat of tank sealant on the top flange and can be good little workers and install the pop rivets wet so that they all work out. Now the fun begins as we have to work with that loved by all tank sealant by Braille to fill the six large holes (four corners and the two at the bend in the top), then cover all the rivets and seams again with out being able to see the work. I may have short arms but it is about all that I can do to reach the other end of the tank through the small inspection hole, there is no way to see as the arm takes almost all the room in the hole. Yes we could use long sticks and we can check our work with a mirror if you have one that long so I guess we are all just a bunch of winners when we complain about the fuel tank design. It has been a topic here several times, Van's took months to come up with a fix and people are still having plastic problems.

We ask for help and solutions and you kindly tell us that there is no problem.

Best regards,
Vern

Peterk said:

Ya know Tom, I had a guy in Ft Worth call me after I finished my 12 and asked if I thought there would be any market for a fiberglass/carbon fiber tank. I told him I would buy one tomorrow. He even came over and took measurements etc. He had replaced the gas tank in his own car with such a tank. Never heard from him again. I'm kinda like you. Van's did it because they are metal people. But you would think the aftermarket opportunity would excite somebody...apparently not.

Click to expand...

Pete- I thought I'd add my 2 cents to the great RV-12 gas tank debate. Your idea about a fiberglass replacement tank sounds good, but I know that the RANS folks had problems with fiberglass tanks in their earlier S-7's. Their solution was to go to polyethylene wing tanks. The problem with the fiberglass tanks was caused by the ethanol that most of us will have to use in the auto gas that we buy. The polyethylene tanks work just fine with ethanol ( I had them in my RANS S-7 for 3 years- no problems). Having said that, however, a polyethylene tank would be VERY expensive to produce, especially for such a relatively small production run. If someone DOES produce a plastic tank, I'll be at the head of the line to buy one! Steve

vernhendershott said:

Van's took months to come up with a fix and people are still having plastic problems.

We ask for help and solutions and you kindly tell us that there is no problem.

Best regards,
Vern

Click to expand...

Vern,

I am truly sorry that nothing happens fast enough for you... and that nothing is designed well enough for you... and that nothing goes together easy enough for you.

Maybe this is not how you really feel, but if anyone takes a look through most of the post that you have made in the past, that is the conclusion they have to come too. (my opinion anyway).
I truly am sorry you have to feel that way because I am sure it makes building an airplane a very frustrating experience. Hearing all of your complaints certainly frustrates me.

Building an airplane (even with a kit as advanced as the RV-12 ) is no simple matter. If anyone expects it to be, please don't try it.

The point of my previous post was to point out that if a large number of people succeed at a specific task and a few do not does that mean it should be re-engineered?
I know people that have stripped out the threads for the oil drain plug on their car. Should the car makers redesign the process for changing the engine oil? Not likely.

Now I will try and be helpful...
When installing the top cover on your fuel tank, cover all of the sidewall flanges with a smoothed layer of tank sealant that it about 1/32" thick.
Place a large blob (about 3/4" in diam) into each corner on the interior surface. Do the same at the break in the top flange on each side where the bend occurs in the top cover. Place a smaller blob (about 1/2 the size of the ones previous) directly over the 6 breaks in the flange on the outside of the tank (the same locations where you just blobbed the interior) Cleco on the cover and install all rivets coated with a small amount of sealant. Lay the tank upside down. Insert a bright flashlight in the tank. Use a popsicle stick to smooth/slightly spread the 6 blobs on the interior.
If the tank leaks along the top...disassemble and carefully follow the above steps again.


P.S. The only plastic problems I have seen is builders not getting it seal properly. I do not think that is the fault of the plastic.


(about as good of) regards (that I can give at the moment)

Scott

steve wyman said:

Pete- I thought I'd add my 2 cents to the great RV-12 gas tank debate. Your idea about a fiberglass replacement tank sounds good, but I know that the RANS folks had problems with fiberglass tanks in their earlier S-7's. Their solution was to go to polyethylene wing tanks. The problem with the fiberglass tanks was caused by the ethanol that most of us will have to use in the auto gas that we buy. The polyethylene tanks work just fine with ethanol ( I had them in my RANS S-7 for 3 years- no problems). Having said that, however, a polyethylene tank would be VERY expensive to produce, especially for such a relatively small production run. If someone DOES produce a plastic tank, I'll be at the head of the line to buy one! Steve

Click to expand...

So Steve...my question is: what are the chances of each of us making our own polyethylene tank? We made airplanes...why couldn't we make polyethylene tanks? Obviously it would take instruction, but I for one would travel to "two weeks to tank" in a heart beat. We go to repairman's school, Oshkosh, Oregon, Lakeland...why not tank school. We need an instructor.

Peterk said:

So Steve...my question is: what are the chances of each of us making our own polyethylene tank? We made airplanes...why couldn't we make polyethylene tanks? Obviously it would take instruction, but I for one would travel to "two weeks to tank" in a heart beat. We go to repairman's school, Oshkosh, Oregon, Lakeland...why not tank school. We need an instructor.

Click to expand...

Poly tanks are typically rotary molded.

The development cost for a mold for a part similar to an RV-12 tank would be 10s of thousands of dollars. Assuming a way could be found to mold in the interior baffles that are needed (remember those parts that you installed in the fwd bottom of the tank). I am not saying it could not be done but the whole thing would be very expensive

What ever happened to welded tanks?

There was a discussion last summer about fabricating welded tanks. Several expressed interest. Did anyone ever actually build one?

rvbuilder2002 said:

Poly tanks are typically rotary molded.

The development cost for a mold for a part similar to an RV-12 tank would be 10s of thousands of dollars. Assuming a way could be found to mold in the interior baffles that are needed (remember those parts that you installed in the fwd bottom of the tank). I am not saying it could not be done but the whole thing would be very expensive

Click to expand...

Yikes! I'll wait for you to have one of your brilliant brainstorms in the middle of the night. You can do it Scott! By the way, I now have my prop turn down to under 20 (at 35 degrees) thanks to your tip.

Mark Henderson said:

There was a discussion last summer about fabricating welded tanks. Several expressed interest. Did anyone ever actually build one?

Click to expand...

Mark,

Don't quote me, but i remember a conversation about the tank aluminum being too thin to hold a weld. Thicker metal would mean more weight.

rvbuilder2002 said:

Vern,

I am truly sorry that nothing happens fast enough for you... and that nothing is designed well enough for you... and that nothing goes together easy enough for you.

Maybe this is not how you really feel, but if anyone takes a look through most of the post that you have made in the past, that is the conclusion they have to come too. (my opinion anyway).
I truly am sorry you have to feel that way because I am sure it makes building an airplane a very frustrating experience. Hearing all of your complaints certainly frustrates me.

Building an airplane (even with a kit as advanced as the RV-12 ) is no simple matter. If anyone expects it to be, please don't try it.

The point of my previous post was to point out that if a large number of people succeed at a specific task and a few do not does that mean it should be re-engineered?
I know people that have stripped out the threads for the oil drain plug on their car. Should the car makers redesign the process for changing the engine oil? Not likely.

Now I will try and be helpful...
When installing the top cover on your fuel tank, cover all of the sidewall flanges with a smoothed layer of tank sealant that it about 1/32" thick.
Place a large blob (about 3/4" in diam) into each corner on the interior surface. Do the same at the break in the top flange on each side where the bend occurs in the top cover. Place a smaller blob (about 1/2 the size of the ones previous) directly over the 6 breaks in the flange on the outside of the tank (the same locations where you just blobbed the interior) Cleco on the cover and install all rivets coated with a small amount of sealant. Lay the tank upside down. Insert a bright flashlight in the tank. Use a popsicle stick to smooth/slightly spread the 6 blobs on the interior.
If the tank leaks along the top...disassemble and carefully follow the above steps again.


P.S. The only plastic problems I have seen is builders not getting it seal properly. I do not think that is the fault of the plastic.


(about as good of) regards (that I can give at the moment)

Scott

Click to expand...

Hi Scott,

Quote Scott "I am truly sorry that nothing happens fast enough for you... and that nothing is designed well enough for you... and that nothing goes together easy enough for you."

I think you will find that I have only originated two or three complaints on this forum and one of those was the first week working on the wings kit when we found a production mistake on one of the spars. I have agreed with others when they have complained about issues particularly about the fuel tank, that is true.

Quote Scott "Maybe this is not how you really feel, but if anyone takes a look through most of the post that you have made in the past, that is the conclusion they have to come too. (my opinion anyway).
I truly am sorry you have to feel that way because I am sure it makes building an airplane a very frustrating experience."

I think that if you would take the time to in fact look through my posts here you would find, as I just did, that less than 20% were negative or involved a complaint. I have posted about 135 times on about 90 threads and as over 80 % were positive or constructive it would seem that your opinion of me is somewhat colored by something other than the facts. Yes building is a fun experience and building my first RV-12 was a great deal of fun except for the 12 or so days that triggered the under 20 negative posts.

Quote Scott, "Hearing all of your complaints certainly frustrates me."

I am sorry to cause you frustration it is not intended to be personal when any of us comment about issues with the RV-12 or Van's as an institution.


Quote Scott, "The point of my previous post was to point out that if a large number of people succeed at a specific task and a few do not does that mean it should be re-engineered?"

As we only have 17 RV-12's flying and three of them are factory ships this does not seem like a large number to me, I know you are lumping all of the RV wing tanks in but they are very different tanks. I would guess that there are less than 50 tanks for the RV-12 that have been worked on and less that have been sealed and tested, so I think that until we get some significant number of tanks flying and some of those with a considerable number of flight hours it would be hard to declare the RV-12 tank an engineering success. It might be interesting for you to look through all of the fuel tank related threads here and see how many of your customers who actually have fuel tanks in hand have indicated their concerns about the tank or the desire for some fuel tank that they would have more confidence in.

Quote Scott, "Now I will try and be helpful...
When installing the top cover on your fuel tank, cover all of the sidewall flanges with a smoothed layer of tank sealant that it about 1/32" thick.
Place a large blob (about 3/4" in diam) into each corner on the interior surface. Do the same at the break in the top flange on each side where the bend occurs in the top cover. Place a smaller blob (about 1/2 the size of the ones previous) directly over the 6 breaks in the flange on the outside of the tank (the same locations where you just blobbed the interior) Cleco on the cover and install all rivets coated with a small amount of sealant. Lay the tank upside down. Insert a bright flashlight in the tank. Use a popsicle stick to smooth/slightly spread the 6 blobs on the interior.
If the tank leaks along the top...disassemble and carefully follow the above steps again

Thank you for the constructive information I am sure it will be helpful on my next RV-12 kit that was due to ship in mid December, I hope it will ship soon and that Van's will have all shipments back on schedule very soon.

I do have one question on the part where you say " Use a popsicle stick to smooth/slightly spread the 6 blobs on the interior." How do you see where the blob is so that you do not move it or over work it with you arm blocking your line of site to the inside of the tank? I found it very hard do small detail corrections or smoothing when I could not see any of what I was doing. I also found it hard on the inside of the top to do a good job of coating the rivets and overlaying the seams due to the lack of vision.

On my first tank the blob in the top corner behind the site gage leaked because it was not possible to see the area well enough to see that the tank sealant had not pressed all the way to the tank skin leaving a tunnel for an air leak. It is now fixed but as you know it is no fun fixing tank sealant issues.

Have a good day.

Best regards,
Vern

vernhendershott said:

I do have one question on the part where you say " Use a popsicle stick to smooth/slightly spread the 6 blobs on the interior." How do you see where the blob is so that you do not move it or over work it with you arm blocking your line of site to the inside of the tank? I found it very hard do small detail corrections or smoothing when I could not see any of what I was doing.

Click to expand...

As I already mentioned...
Turn it upside down.
Put a bright flashlight inside (Aim the light where ever you are working).

The diam. of the access hole is almost double the diam of most peoples forearms. I double over a thick towel and drape it over the edge of the hole as a pad to push my arm against. I if you are unable to see with your arm positioned to one side of the opening then maybe seek out a helper with a smaller diam arm.

vernhendershott said:

I also found it hard on the inside of the top to do a good job of coating the rivets and overlaying the seams due to the lack of vision.

Vern

Click to expand...

The construction manual doesn't instruct you to do this.

Peterk said:

Yikes! I'll wait for you to have one of your brilliant brainstorms in the middle of the night. You can do it Scott! By the way, I now have my prop turn down to under 20 (at 35 degrees) thanks to your tip.

Click to expand...

Glad to help.
Rotax's instruction is not very clear or detailed "Turn prop numerous times in direction of normal rotation"

Plugging the leak

Here is a suggestion for fixing a fuel tank leak, although I have never tried it. Smear some tank sealant on the inside of the tank in the area of the leak. Rotate the tank so that gravity will pull the sealant towards the leak. On the outside of the tank, use a shop vac to suck the sealant into the leak. I do not know if this will work or not. But it will not take long to try. If it works, it will save lots of time and effort.
Joe

plugging the leak

Can MEK be used to thin the sealant? That way the sealant would flow into the leaks when using the shop vac.

tank woes

Thanks to all who responded thus far. I have removed the tank top and as several of you have said it was not a big deal. I have looked at the inside of sight glass mount and am convinced I have several locations on the aft side of glass that MAY be sucking air. Will put more goop on those areas,but feel thr real culprit (me , of course) is that I may have some tunnels, if you will, channeling up past the screws. So next step will be to remove screws one at a time and squeeze all I can get in the holes and re-assemble screws. I will post results here in about a week after next air test results.
One comment on this issue. I know there are those who apparently had no difficulty at all with these tanks. (Scott for example), but it seems to me that there are a lot more builders saying otherwise. After building an RV6A and enjoying the build as well as the flying it's my opinion that this RV12 kit is near perfect with the exception of the tank, of course. Based on what I've experienced and heard about from y'all I wonder why this issue has not been more effectively addressed by the designers? After all is said and done IF these new sight glasses are prone to future cracks and leaking I would be very concerned should that eventual leak occur while flying filling the cockpit with volatile fumes.
Dick(missing my 6A, but loving the potential in the RV12}

I don't have the demintions of th 12 tank but you may want to look at rciracing.com, then go to aluminum 1 or 2. I used there 8 gal. cell on my fisher avenger and love it.

Ron Russ RV-9, Rv-12 starting

My problem with the tank was self induced. I didn't mix in enough hardener so the sealant didn't cure. I had everything assembled but the top. After drilling out a couple of sections and trying to clean them, we popped adult beverages and ordered a new tank. We are thinking the second one should go better. The old tank is on the shelf, covered with nearly-amusing graffiti about my tiny mistake.

This might be worthy of a second look. I quote from their webpage.

"ATL's tank moldings can include integral sumps, threaded inserts, baffles, metallic flanges, bosses, hose attachment "stubs" and mounting brackets."

Everything that Scott McDaniels mentioned in his post.

http://www.atlinc.com/rotomolded.html

Been looking at using one of these tanks. http://www.incaproducts.com/site/fueltanks_squarerectangular.aspx

These are production tanks, No molds needed.

Yikes!!

As far as the gas tank goes, I've finished all but the top of the fuel tank and the site window. I put it aside till my fuselage is rightside up again so I can set it in and locate the cutout on top.

I've already thought of ordering a new tank ... because it's such a mess and I can't imagine it not leaking ... even before I get to the balloon testing.

And I thought I was having enough aggrevation with the Adel cushioned clamps ... but that's another story ...

Jeromiemead said:

Been looking at using one of these tanks. http://www.incaproducts.com/site/fueltanks_squarerectangular.aspx

These are production tanks, No molds needed.

Click to expand...

It sure would be nice if we could buy a production tank but the molded tanks that I have seen lack the REQUIRED internal baffle. Mounting the tank like supplied RV-12 tank is another issue.

Jumping in again

Marty makes a VERY important point. You are very likely NOT going to find a tank with the baffle placed as desired and all the other requirments. To me the ONLY issue with this tank has been the window. After inspection, close it up, install a mechanical gauge on top, and the worry and problems should be minimized. The tank works. I think everyone is chasing their tail here. Do the tank as instructed, then if not satisfied, do as I suggested above, and be done with it.

John Bender

LETS HEAR FROIM THE MAN

I have just ordered my 12, two friends were to order at the same time but absolutely refuse to until the tank issue is resolved. (they call me adventurous)
There must be some reason we haven't heard from Van or his people. If building as a ELSA it is my understanding that after inspection your can change the tank under a 337. Mel am I correct. John

JEG said:

If building as a ELSA it is my understanding that after inspection your can change the tank under a 337. Mel am I correct. John

Click to expand...

After issuance of the airworthiness certificate, you may make any modification you like as long as the mod doesn't take the aircraft out of LSA parameters.
337s are only used for certificated aircraft.

Anyone having trouble with or thinking it will tax your nerves to the end to build the gas tank please contact me. I will assemble your tank, leak check it and return it in 5 days! Cost,,,$300.00 plus shipping I will also build any part or all of your RV-12 and do it in 8 weeks or less. Call for a price. 903-945-5120 ask for Chuck Now building second -12

Part two:Last Sunday after removing top for access I spotted sealant on all likely suspect areas. tested 4 days later, and sight glass still likes to bubble up the soapy indicator.
Have now removed all 22 holding screws and pumped the sealant into the holes. Then coated the screws with ample sealant and re-assembled. Will report on test results of this effort next Tuesday.
By the way it is almost impossible to seal the top for testing with clecos and tape, but overcame that by introducing sufficient air from compressor to just expand the balloon enough to show positive pressure.
Dick

How are the tanks on the RV7 and 9 different than the 12? I know they're larger, but are they of the same general design?

diamond said:

How are the tanks on the RV7 and 9 different than the 12? I know they're larger, but are they of the same general design?

Click to expand...

The RV-7 & -9 have integral wing leading edge tanks.
The RV-12 used an individual tank mounted in the baggage compartment.

it's official ...

It's official ... my window leaks! I put the tank down on it's window side, added water and it leaks. Now I realize I shouldn't have attached the top before my water test. It's too late now. Since I'm out of fuel tank sealant at the present time there's nothing I can do about it today.

I wish I could just seal the entire window area and be done with it.

I imagine I'll remove the top, order sealant and solid rivets (order a new window & new reflector plate?) and try again.




Later ...same day ...

I removed the top of the gas tank (lots of solid rivets to drill out), washers, nuts & screws around the window but I can't get the window and reflector plate off with out damaging them. Therefore, I think I'll wait for the sealant to arrive, then I'll slather sealant into the cutouts in the window where the screws fit into, on all the screws, nuts and washers and hope that does the job. If not I'll build a new tank with all new parts. I'm not the first to have to do that and I probably won't be the last.

Even though I wish there was no window ... this failure seems to be entirely mine. Others have successfully completed this task and I would guess I just didn't use enough sealant the first time around. Oh well ...

Leaks

Jerry,

Did you do a 'balloon' test first? I am wondering if that was OK or if you went directly to the water test. I did a 3 or 4 day balloon test and that was OK but I wasn't going to do any liquid test, but after your experience I may put a gallon or two of gas in and let it rest of each side for a day or so and see if that confirms what the balloon test showed.

John,

I just added water, before I put the circular plates on (fuel sender being one of those). No balloon test as of yet.The window leaked in 2 spots, I think, then I tightened the screws "a wee bit more" and only a drop in one spot came out ever so slowly.

Now looking for 5/32 or 3/16 solid pop rivet to fill a few drilled out rivets in the top skin. Noone said it was going to easy ... especially for a first time builder.

Jerry

Leaky tank woes

See my post:
http://www.vansairforce.com/community/showthread.php?t=25556&highlight=fiberglass+tank

I've had these tanks filled with either avgas or mogas for nearly two years now, and no problems, and no leaks.

All the Eze aircraft have had glass tanks for years with zero problems.

I am not a builder, but having had a VariEze for many years, I thought, why not fiberglass tanks; and my aluminum-skinned tanks have been the solution for me. Maybe the best of both worlds, eh?

A short story of building things: Many years ago, me old Dad was a carpenter superintendent on many heavy construction jobs and was often approached by men wanting work. His interview consisted of asking applicants to build one of two things, a good usable sawhorse, or a 1' square box. Few had any idea how to build a sawhorse, and many tried the box - few passed muster. One outsanding applicant, "No problem." And, in a few minutes said applicant had constructed a perfect box held together (temporarily) only by the perfectly cut 1' squares each cut on a 45 degree angle so as to fit together perfectly. The old man told him that lunch was from 12:00-12:30, start work, now.

Similarly to build a box of aluminum sheet metal is a daunting task; and a leak proof box to hold fuel is even more so daunting. But, fiberglass tanks, however sloppily built, if there's enough resin everywhere, most likely won't leak.

Standing back for the flames from aluminum construction purists.

Barney, in Memphis

I like the engineering on the 12 a lot. The one aspect that has troubled me from the start is a big riveted aluminum box full of very volatile fuel sitting right behind my head. There are too many NTSB reports of minor accidents which turned fatal when the fuel tanks ruptured. The Van's tank is very light, and it is always great to save weight. If you showed up at any track with a car that had that for a tank, they wouldn't even let you off the trailer. A real fuel cell is too heavy, but there are alternatives. I have a friend who builds winery equipment who is doing some preliminary design work for a welded tank with safety foam. It will weigh more, and be more expensive. I will be curious to see exactly what the numbers are.

After all my fussing the fuel tank came out pretty good. I had 4 leaks initially. one at the ballloon connection, one at the air valve connection and two on the cover screws. I tightened the clamps at the connections and gave the screws a 1/4 turn, then it remained airtight for two days ( I measured the circumference of the balloon ). Don't know if it will hold liquid though.
I primed the tank, including around the windows. It looks pretty good. I had only one tiny spot that leaked sealant and got no paint on the glass. I masked the glass with dots of cardboard from a Christmas sweater box. I used a 1/4" deep socket as die to cut them out and they fit perfectly. Then just popped them out after painting.
You can see this on http://www.Mykitlog.com/ARPENN

Art Pennanen

Mark Henderson said:

I like the engineering on the 12 a lot. The one aspect that has troubled me from the start is a big riveted aluminum box full of very volatile fuel sitting right behind my head. There are too many NTSB reports of minor accidents which turned fatal when the fuel tanks ruptured. The Van's tank is very light, and it is always great to save weight. If you showed up at any track with a car that had that for a tank, they wouldn't even let you off the trailer. A real fuel cell is too heavy, but there are alternatives. I have a friend who builds winery equipment who is doing some preliminary design work for a welded tank with safety foam. It will weigh more, and be more expensive. I will be curious to see exactly what the numbers are.

Click to expand...

I have an aquaintance who has taken the measurements/baffles everything and is prepared to make aftermarket fiberglass for $375. The problem is: if you go ELSA you have to build the tank as is, get it certified, then change it. In my case (and several others) once we got the existing tank not to leak, we covered the sight holes (the source of all the leaks) and all is well. Replacing it now for $375...and the weight change...is not a real popular idea. I think if Van's ever has it put on the 51% list you might get more interest. Then you could put it in from the beginning and not even buy the other one.

Air versus liquid test

It is better to do an air test first. Air will leak through a much smaller hole than water will. If the tank does not leak air, then it will not leak water either. If an air test is not done and there is a very small hole that does not leak water, then that hole might get bigger with time. A very small hole might not leak liquid gasoline but could leak gasoline vapor.
Joe

yikes!

Today I reworked my fuel tank. I used the qt. sealant can and mixed it 10 to 1 using a weight watchers scale for the weight proportions. I have a hunch my sealant will never set up. I must have messed up again. A note came with the qt. sealant

"that it will take up to 3-7 days to cure and will remain soft for up to 30 days in cool weather ... be patient! Van's"

The little jars and caulking tubes of sealant I used before, set up in about 2-3hours. I'll give this stuff a few days and see if anything begins to set up. Here's hoping it does eventually set up and then doesn't leak.

I'll be very surprised and happy if all goes well. May just have to build another tank.